But having experienced how counterproductive that can be, he decided to go one step further than simply coming out at work and two years ago set up legal sector LGBT+ initiative The Glass Network.
“When you’re in the closet, half your time is spent doing your job and the other half is spent thinking about what you’re not going to say,” Mr McCusker, who is currently a trainee at Jackson Boyd, explained.
“When it comes to a colleague asking what you did at the weekend you have to think about which pronouns to use.
“A lot of time is wasted when people are in the closet but you need visibility [of other LGBT+ people] more than anything else [before others will also come out].”
Visibility is something The Glass Network achieved last week when it won the CSR Award at The Herald’s Law Awards of Scotland.
This matters, Mr McCusker said, because “you can’t be what you can’t see”. This first hit home for him when he was working as an administrative assistant at Drummond Miller in 2015 and realised that he “didn’t know what an LGBT+ lawyer could achieve”.
The Glass Network hopes to address that by showing that there are numerous LGBT+ role models in the legal profession and wider business community, although Mr McCusker admitted that it could be a slow process.
“There’s a difficulty in it because you don’t want to go up to someone and say ‘you’re a lesbian, now talk about it’,” he said.
“If we can prove that The Glass Network is successful and useful then hopefully people will come out of the closet and we can highlight the achievements of the LGBT professionals [and their impact on] the profession and the Scottish economy.
“Hopefully we’ll have more role models coming out, but that will take a bit more time.”
Although Mr McCusker, whose traineeship began last year, is right at the start of his legal career, he said younger people are increasingly interested in “taking control of what kind of legal profession they want to go into”.
“They want their business to have the same values as them,” he explained.
That said, he admitted to being nervous when initially launching the network, not least because his parents felt he could be making himself visible for all the wrong reasons.
“My mum and dad told me not to do it – they wanted me to focus on getting a traineeship,” he said.
“They thought if I started being a rights activist I would be seen as a problem rather than someone who’s employable.
“I understood that but I wanted to add to the profession too.
“It was sad for me coming into the profession and not seeing [LGBT+ role models] there.
“It was also an obvious opportunity – I could be that person.”
Having already enlisted the likes of First Minister Nicola Sturgeon and law commissioner Hector MacQueen in a high-profile campaign aimed at promoting LGBT+ equality in the workplace, Mr McCusker is now focusing on ensuring The Glass Network can have a positive impact on businesses right across Scotland.
In the short term, that means hosting an event with Brewgooder – the craft beer firm that donates its profits to clean water charities around the world –that will focus on the benefits of corporate social responsibility more generally.
The plan for next year is to hold a conference for law firms of all sizes and from all parts of Scotland to discuss how having an LGBT+ inclusion strategy could benefit their businesses as well as their people, with The Glass Network acting as “the external network that’s accessible to everybody”.
“In Scotland we are very pro-diversity,” Mr McCusker said. “If you look at things like the Scotland Act it’s in our bones, but people feel quite apathetic to the whole thing.
“They just assume that everything is fine, but that’s part of the problem.
“When it comes to women in law or black and minority ethnic legal professionals you can see them. People who are LGBT+ have been invisible because you can’t spot them. They haven’t been given much of a voice.”